1. Technical Field
The present disclosure relates to a waterproof paper. More particularly, the present disclosure relates to a biodegradable waterproof paper and a manufacturing method for the same.
2. Description of Related Art
To meet the increasing environmental consciousness, the issues of food safety and the disposable food packaging have become increasingly stringent. Replacing environmental-unfriendly materials (such as plastic, styrofoam, etc.) by biodegradable materials is a present trend to reduce the burden on the Earth's environment.
Since paper materials are not waterproof and greaseproof, the food contact surfaces of paper-based containers are usually coated by an insulation layer, such as wax, or PE film, to achieve the waterproof and greaseproof purposes.
Some biodegradable materials such as starch, and polylactic acid . . . etc. has been developed as lamination films to provide a waterproof or greaseproof layer of a paper material.
FIG. 1 is an operational scheme of prior art. The conventional polylactic acid (PLA) coated paper is manufactured by extruding method. In this method, PLA masterbatches (solid) are heated to form a hot molten PLA 200 (thick liquid) is directly extruded onto a chill roller 42, and then a paper 10 passed through the small space between the chill roller 42 and a pressure roller 41. Consequently, the molten PLA resin 200 is covered on the paper 10 to form a waterproof film 20 and the paper with waterproof film is collected by a roller 50. FIG. 2 is a cross-sectional view of a waterproof paper made by extruding method as described in FIG. 1. The waterproof paper made by extruding method includes a paper 10 and a PLA film 20 separately covered on surface of the paper 10.
Since the output of the molten PLA 200 is controlled by an extruding machine 30, the excess amount of the molten PLA 200 outputted from the extruding machine 30 is necessary for controlling the biodegradable film uniformity, so that the PLA consumption is increased and an unnecessary thicker biodegradable film is obtained. Furthermore, since the PLA coated film is laminated onto the paper surface by heat and pressure, so that only weak adhesion strength between the PLA coated film and the paper. If the conventional PLA coated paper is applied to reuse bags, such as drug bags, or fruit bags, the PLA coated film may be peeled from the paper bags because the insufficient adhesion strength between the PLA coated film and the paper of the paper bags.